Ageing is the primary risk factor for most chronic diseases including type 2 diabetes mellitus. Sarcopenia and muscular mitochondrial dysfunction with aging are crucial mechanisms leading to decreased exercise tolerance and worsened insulin sensitivity. Thus, metabolic disease and frailty, which limits physical mobility as well as quality of life, share common cellular mechanisms.

The investigators will test the hypothesis that a combination of normobaric hypoxia and exercise training elicits a synergistic effect on age-associated metabolic skeletal muscle dysfunction and the investigators will address the molecular mechanisms. In a randomized clinical study, the investigators will compare normoxic and hypoxic training conditions in elderly subjects. Outcome measures will focus on whole body insulin sensitivity and mitochondrial responses in skeletal muscle before and after the 8-week training intervention.

Inclusion Criteria:

• 55 to 75 years of age
• body mass index: 20 - 35 kg/m2
• weight stable during last 6 months before screening (weight change < 2% body weight)
• HOMA-index of insulin resistance ≥ 2 to 4 units

Exclusion Criteria:

• more than 1 hour of scheduled exercise training per week
• known diagnosis of type 2 diabetes or measured HbA1c > 6,5%
• known drug or alcohol abuse
• any contraindication to perform exercise training
• acute or chronic infections
• increased bleeding risk by history, INR > 1,3, use of anticoagulants